Predictive performance of multi-model ensemble forecasts of COVID-19 across European nations

Background: Short-term forecasts of infectious disease contribute to situational awareness and capacity planning. Based on best practice in other fields and recent insights in infectious disease epidemiology, one can maximise forecasts' predictive performance by combining independent models into an ensemble. Here we report the performance of ensemble predictions of COVID-19 cases and deaths across Europe from March 2021 to March 2022.

Methods: We created the European COVID-19 Forecast Hub, an online open-access platform where modellers upload weekly forecasts for 32 countries with results publicly visualised and evaluated. We created a weekly ensemble forecast from the equally-weighted average across individual models' predictive quantiles. We measured forecast accuracy using a baseline and relative Weighted Interval Score (rWIS). We retrospectively explored ensemble methods, including weighting by past performance.

Results: We collected weekly forecasts from 48 models, of which we evaluated 29 models alongside the ensemble model. The ensemble had a consistently strong performance across countries over time, performing better on rWIS than 91% of forecasts for deaths (N=763 predictions from 20 models), and 83% forecasts for cases (N=886 predictions from 23 models). Performance remained stable over a 4-week horizon for death forecasts but declined with longer horizons for cases. Among ensemble methods, the most influential choice came from using a median average instead of the mean, regardless of weighting component models.

Conclusions: Our results support combining independent models into an ensemble forecast to improve epidemiological predictions, and suggest that median averages yield better performance than methods based on means. We highlight that forecast consumers should place more weight on incident death forecasts than case forecasts at horizons greater than two weeks.

Funding: European Commission, Ministerio de Ciencia, Innovación y Universidades, FEDER; Agència de Qualitat i Avaluació Sanitàries de Catalunya; Netzwerk Universitätsmedizin; Health Protection Research Unit; Wellcome Trust; European Centre for Disease Prevention and Control; Ministry of Science and Higher Education of Poland; Federal Ministry of Education and Research; Los Alamos National Laboratory; German Free State of Saxony; NCBiR; FISR 2020 Covid-19 I Fase; Spanish Ministry of Health / REACT-UE (FEDER); National Institutes of General Medical Sciences; Ministerio de Sanidad/ISCIII; PERISCOPE European H2020; PERISCOPE European H2021; InPresa; National Institutes of Health, NSF, US Centers for Disease Control and Prevention, Google, University of Virginia, Defense Threat Reduction Agency.

Are there predictor variables for the diagnosis of transthyretin cardiac amyloidosis?

Introduction

Transthyretin cardiac amyloidosis (ATTR) can be reliably diagnosed in the absence of histology if grade 2 or 3 cardiac uptake is demonstrated on 99mTc-DPD scan (DPD) in the absence of a detectable monoclonal component. Diagnosis requires a high degree of clinical suspicion in the presence of often non-specific findings and that it may be one of the reasons to under-diagnose ATTR. The aim of the study is to identify clinical, analytical and ECG variables that best predict a positive DPD result.

Methods

This is a multicentre retrospective study including all patients undergoing consecutive 99mTc-DPD scintigraphy in a reference area of 750,000 inhabitants between January 2016 and January 2021 for suspected ATTR. AL amyloidosis patients were excluded. Clinical, analytical, ECG and echocardiographic data were analyzed. We identified variables that independently predicted a positive DPD study using a multivariable logistic regression analysis. Receiver Operating Curve (ROC) analysis and the Area under the Curve (AUC) were calculated to assess the discrimination capacity of the model to predict a positive DPD study.

Results

DPD scans from a total of 181 patients were analyzed. Mean age of the sample: 78 years (42–96), 100% caucasians, 77% male. 54.7% (N=99) had a positive DPD study (defined as grade 2 or 3 Perugini uptake) and 45.3% (N=82) were negative. Independent predictors of a positive study were age, male gender, left ventricular septum thickness, any grade of atrioventricular block, low QRS voltage, Carpal tunnel syndrome, history of hypotension or need to lower antihypertensive drugs and a NT-proBNP value above 1800 pg/ml (See Table 1). The diagnostic accuracy of the model was excellent, with an AUC of 0.92 (IC 95% 0.87–0.96) (see Figure 1).

Conclusions

There are clinical-analytical factors and ECG and echocardiogram findings accessible in daily clinical practice that are able to predict a positive result on cardiac scintigraphy requested for suspected ATTR. Identifying these factors may improve the non-invasive diagnosis of ATTR.

Funding Acknowledgement

Type of funding sources: None. Table 1. Multivariable logistic regression analysFigure 1. ROC curve

The role of thyroid hormones as inductors of oxidative stress and neurodegeneration

Reactive oxygen species (ROS) are oxidizing agents amply implicated in tissue damage. ROS production is inevitably linked to ATP synthesis in most cells, and the rate of production is related to the rate of cell respiration. Multiple antioxidant mechanisms limit ROS dispersion and interaction with cell components, but, when the balance between ROS production and scavenging is lost, oxidative damage develops. Many traits of aging are related to oxidative damage by ROS, including neurodegenerative diseases. Thyroid hormones (THs) are a major factor controlling metabolic and respiratory rates in virtually all cell types in mammals. The general metabolic effect of THs is a relative acceleration of the basal metabolism that includes an increase of the rate of both catabolic and anabolic reactions. THs are related to oxidative stress not only by their stimulation of metabolism but also by their effects on antioxidant mechanisms. Thyroid dysfunction increases with age, so changes in THs levels in the elderly could be a factor affecting the development of neurodegenerative diseases. However, the relationship is not always clear. In this review, we analyze the participation of thyroid hormones on ROS production and oxidative stress, and the way the changes in thyroid status in aging are involved in neurodegenerative diseases.

Operator space theory: a natural framework for bell inequalities

In this Letter we show that the field of operator space theory provides a general and powerful mathematical framework for arbitrary Bell inequalities, in particular, regarding the scaling of their violation within quantum mechanics. We illustrate the power of this connection by showing that bipartite quantum states with local, Hilbert space dimension n can violate a Bell inequality by a factor of order sqrt[n]/(log{2}n) when observables with n possible outcomes are used. Applications to resistance to noise, Hilbert space dimension estimates, and communication complexity are given.

Static and dynamic compressive strains influence nitric oxide production and chondrocyte bioactivity when encapsulated in PEG hydrogels of different crosslinking densities

OBJECTIVE

Mechanical loading is an important regulator of chondrocytes; however, many of the mechanisms involved in chondrocyte mechanotransduction still remain unclear. Here, poly(ethylene glycol) (PEG) hydrogels are proposed as a model system to elucidate chondrocyte response due to cell deformation, which is controlled by gel crosslinking (rho(x)).

METHODS

Bovine articular chondrocytes (50 x 10(6)cells/mL) were encapsulated in gels with three rho(x)s and subjected to static (15% strain) or dynamic (0.3 Hz or 1 Hz, 15% amplitude strain) loading for 48 h. Cell deformation was examined by confocal microscopy. Cell response was assessed by total nitric oxide (NO) production, proteoglycan (PG) synthesis ((35)SO(4)(2-)-incorporation) and cell proliferation (CP) ([(3)H]-thymidine incorporation). Oxygen consumption was assessed using an oxygen biosensor.

RESULTS

An increase in rho(x) led to lower water contents, higher compressive moduli, and higher cell deformations. Chondrocyte response was dependent on both loading regime and rho(x). For example, under a static strain, NO was not affected, while CP and PG synthesis were inhibited in low rho(x) and stimulated in high rho(x). Dynamic loading resulted in either no effect or an inhibitory effect on NO, CP, and PG synthesis. Overall, our results showed correlations between NO and CP and/or PG synthesis under static and dynamic (0.3 Hz) loading. This finding was attributed to the hypoxic environment that resulted from the high cell-seeding density.

CONCLUSION

This study demonstrates gel rho(x) and loading condition influence NO, CP, and PG synthesis. Under a hypoxic environment and certain loading conditions, NO appears to have a positive effect on chondrocyte bioactivity.

Adalimumab for treating rheumatoid arthritis

BACKGROUND

Adalimumab is a fully human anti-TNFalpha monoclonal antibody. Published studies indicate that its use in patients with RA can be effective and safe.

OBJECTIVES

The aim of this review was to assess the efficacy and safety of adalimumab in the treatment of RA.

SEARCH STRATEGY

Electronic databases were searched up to August, 2004: MEDLINE, CINAHL, EBM Reviews (CDSR, ACP Journal Club, DARE and CENTRAL) and Health STAR. Conference proceedings were hand searched and pharmaceutical companies were contacted to obtain additional unpublished data from published trials. Adalimumab was searched as a text word as it is not currently indexed. The search was not limited by language, year of publication or type of publication.

SELECTION CRITERIA

All randomised controlled trials (RCTs) or controlled clinical trials (CCTs) comparing adalimumab alone or in combination with DMARDs to placebo or other DMARDs.

DATA COLLECTION AND ANALYSIS

Two reviewers independently collected the data in a standardized form and assessed the methodological quality of the trial using validated criteria. Outcome measures included ACR and EULAR responses, DAS 28 and components of ACR response and radiographic data. Safety data were also included. Continuous data were reported as weighted mean difference (WMD) with 95% confidence interval (95%CI), absolute benefit (AB) and relative difference (RD). Dichotomous outcomes were reported as relative risk (RR) with 95% CI, absolute risk difference (ARD) or risk difference (RDiff) with 95%CI and number needed to treat (NNT) or to harm (NNH). When significant heterogeneity was not found, data were pooled.

MAIN RESULTS

Six studies with 2381 patients were included in this review. Two comparisons were done: A. adalimumab subcutaneously (sc) + methotrexate (or DMARDs) versus placebo sc + methotrexate (or DMARDs). B. adalimumab sc in monotherapy versus placebo sc. In the comparison A, with adalimumab 40 mg every other week (e.o.w.), the RR to achieve an ACR 20 response at 24 weeks ranged in the included studies from 1.52 to 4.63, and the NNT ranged from 1.9 to 5.4. The RR (95%CI) to achieve an ACR 50 response was 4.63 (3.04-7.05), and the NNT was 3.0 (95%CI 2.0-6.0). The RR (95%CI) to achieve an ACR 70 response was 5.14 (3.14-8.41) and the number needed to treat was 7.0 (95%CI 5.0-13.0). At 52 weeks, the RRs (95%CI) to achieve an ACR 20, 50, and 70 response were 2.46 (1.87-3.22), 4.37 (2.77-6.91), and 5.15 (2.60-10.22), with NNTs of 2.9, 3.1, and 5.3, respectively. At 52 weeks, adalimumab 40 mg e.o.w. and 20 mg every week (e.w.) significantly slowed the radiological progression including Sharp modified index, erosion score, and joint space score (only with 40 mg e.o.w.). In the comparison B, with adalimumab 40 mg e.o w. , the RRs to achieve an ACR 20, 50, and 70 response at 24/26 weeks were 1.91 (1.17-3.10), 2.84 (1.58-5.12), and 7.33 (2.25-33.90) with NNTs of 5.0 (95%CI 3.0-9.0), 7.0 (4.0-20.0), and 9.0 (3.0-38.0), respectively. In most of the analysed studies and comparisons, there were not significant differences in safety outcomes between adalimumab and control groups. The development of positive antinuclear antibodies was significantly more frequent in adalimumab patients than in placebo patients. Serious infections were significantly more frequent in adalimumab patients in only one study (Keystone 2004) with a RR (95%CI) of 7.64(1.02-57.18) and a NNH of 30.2.

AUTHORS' CONCLUSIONS

On the basis of the studies reviewed here, adalimumab in combination with methotrexate is efficacious and safe in the treatment of the rheumatoid arthritis. Adalimumab 40 mg sc e.o.w. and 20 mg e.w. slows the radiographic progression at 52 weeks. Adalimumab in combination with DMARDs other than methotrexate is also efficacious and safe, even though data from one only study are available and the number of patients in each group is low. Adalimumab in monotherapy is efficacious and safe in the treatment of the rheumatoid arthritis but the effect size is lower than with combined therapy.

Relative efficiency and validity properties of a visual analogue vs a categorical scaled version of the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index: Spanish versions

OBJECTIVE

To compare the performance of visual analogue (VAS) vs categorical (CT) scaled versions of the three subscales (pain, stiffness and difficulty) of the WOMAC Index in patients with knee osteoarthritis.

MATERIAL AND METHODS

Patients with knee OA (at least grade II of Kellgren & Lawrence classification) were treated for a 6-weeks period with an NSAID. The following measures were applied at baseline and after treatment: VAS and CT WOMAC scales, Lequesne Index, pain on VAS, and global assessment by patient and observer. Construct Validity was determined by correlation of each of the subscale scores with the other outcomes both at baseline and after treatment (Pearson's test); responsiveness comparing baseline vs final status by Wilcoxon's test; reliability by analysis of the internal consistency using Cronbach's alpha at baseline and after the treatment period; and test-retest reliability by Kendall's Tau-c statistics. Finally, correlation and analysis of the relative efficiency (RE) between the subscales of both formats were tested.

RESULTS

Seventy-three (8 men and 65 women) patients with a mean disease duration from first diagnosis of 69 months (3 to 254) completed the study. The following were the observed values for the instruments' psychometric properties: (1) construct validity: correlations ranged from 0.30 to 0.84 for VAS and 0.27 to 0.77 for CT subscales; (2) responsiveness: achieved P values for the pain, stiffness and difficulty scales were P<0.0001, P=0.002 and P<0.0001 in VAS and P=0.003, P<0.0001 and P=0.001 in CT format respectively; (3) internal consistency: the obtained Cronbach's alpha coefficients ranged from 0.71 to 0.97 for the VAS and 0.64 to 0.95 for the CT subscales; (4) test-retest reliability: correlation coefficients ranged from 0.36 to 0.76 for VAS and 0.34 to 0.52 for CT subscales; and (5) the relative efficiency of the subscales in VAS vs CT format were 2.20, 0.91 and 1.91 for pain, stiffness and difficulty respectively. Significant correlations between subscales in both formats ranging from 0.72 to 0.86 were observed.

CONCLUSION

We have shown that both the VAS version of WOMAC have adequate evaluative and discriminative properties. We found the pain and physical function scales in VAS format and the stiffness scale in CT format to have a slightly better performance in this sample.

Spanish intercomparisons for individual monitoring

The Spanish Nuclear Safety Council (CSN) carries out an intercomparison programme for individual monitoring every 5 years. The objective is to acquire valuable information on the performance of the dosimetry systems of the participating Spanish approved dosimetry services and to assess precision and accuracy as quality indicators of overall dosimetry performance. CSN has carried out two intercomparison programmes, the last one in 1995, in which 18 approved dosimetry services participated. The dosemeters were exposed to photon fields (137Cs gamma rays and two X ray beams of different qualities), at two standard laboratories in Spain. The irradiations were done for evaluating personal dose equivalent, Hp(10), using the ICRU 47 phantom. Presently, CSN is carrying out a new intercomparison, which will be finished in 2001. Twenty-three dosimetry services will participate; 22 from Spain and one from Cuba. The irradiations will be done in reference photon radiation fields.

The outlook for the application of electronic dosemeters as legal dosimetry

This study analyses new trends of a set of 12 electronic personal dosemeters in order to gain an overview of their main advantages and limitations. Physical characteristics and radiological, mechanical and environmental performance were tested according to IEC-61526 Standard requirements. The study highlights the different behaviour of the selected dosemeters. In particular, it is demonstrated that three of the tested devices fulfilled most of the established requirements, whereas another three of them presented important faults. The parameters that need more development are, in general, the response at low energy photon and beta radiation, and the dose rate alarm features. In some cases, mechanical problems as well as interference in the response due to external electromagnetic fields were also found. However, the results of the study foresee a promising future for the application of the newest personal electronic dosemeters as legal personal dosemeters and show the need for internationally agreed technical requirements within the European countries.

The Spanish National Dose Registry and Spanish radiation passbooks

The Spanish National Dose Registry (BDN) is the Nuclear Safety Council's (CSN) national database of occupational exposure to radiation. Each month BDN receives records of individual external doses from approved dosimetry services. The dose records include information regarding the occupational activities of exposed workers. The dose information and the statistical analysis prepared by the BDN are a useful tool for effective operational protection of occupationally exposed workers and a support for the CSN in the development and application of the ALARA principle. The Spanish radiation passbook was introduced in 1990 and since then CSN, as regulatory authority, has required that all outside workers entering controlled areas should have radiation passbooks. Nowadays, CSN has implemented improvements in the Spanish radiation passbooks, taking into account previous experience and Directive 96/29/EURATOM.

Glucoprivation attenuates the hypophagia induced by epinephrine in mice

It is well known that relatively high doses of epinephrine (E) injected intraperitoneally (IP) produce hypophagia, possibly by an action on liver metabolism. The purpose of the present experiment was to find out if lipoprivation with 2-mercaptoacetate (MA, 800 mumol/kg, IP) or glucoprivation with either 2-deoxy-D-glucose (2DG, 500 mg/kg, IP) or 2,5-anhydro-D-mannitol (2,5-AM, 400 mg/kg, IP) were able to modify the anorectic effect of E (300 micrograms/kg). At the onset of the dark period, mice received a first injection of saline (S) or one of the metabolic blockers mentioned above and, 30 min later, a second injection of S or E; then 30-min food intake was measured. E alone decreased feeding by 80% (p < 0.05); this effect was nearly the same when MA was previously injected. In contrast, in the presence of 2DG or 2,5-AM, E reduced food intake only by 22% and 24%, respectively (not significant). Attenuation of E-induced hypophagia by these blockers suggests the participation of glucose utilization pathways. Because it has been shown that 2,5-AM acts specifically on the liver, we could additionally suggest that E reduces feeding by an action on glucose hepatic metabolism.

[Evaluation of Mexican biomedical journals]

We present the evaluation procedures of Biomedical Journals, performed by the Journal Committee of the Centro Nacional de Información y Documentación sobre Salud (CENIDS) for the preparation of CR-ROM ARTEMISA 2 (Edited health information articles in Mexico), which contains a database of the complete text of articles appearing in the journals of the highest quality published in Mexico.